In the construction of prostheses, in particular false legs, there are a variety of techniques. The primary considerations are of course both technical and cosmetic. Ahead of every aspect, however, the main consideration is service characteristics, namely whether the device is comfortable and functions, since if it does not satisfy both these requirements the patient will not use the prosthesis.
Typically the construction of false limbs is the domain of specialists whose decisions are in part based on intuition and in part on experience. Even when computer technology is applied to the problem of artificial-limb design, it is normally left to the designer to make up the most important part, namely the socalled socket shaft that fits over the patient's stump. This part must fit so that on the one hand it can support the load of the limb and/or of the patient, but also so that when the stump is moved through the full normal range of movement, it remains comfortable. Typically the fitting of the socket entails a lengthy process where the patient's subjective impressions of successive adjustments to the fit are followed, along with direct observations by the maker of the device.
At best such procedures are haphazard. Successive adjustments of socket fit are frequently off the mark and sometimes even make the device less comfortable or reduce the useful range of the limb.